Along with the development of the display technologies, a pixel per inch (PPI) of a display device becomes higher and higher, but a pixel aperture ratio remains unchanged and even it is increased slightly. In order to meet the above-mentioned requirements, a signal line arranged on an array substrate and configured to transmit a signal to a pixel unit becomes thinner and thinner. During the manufacture of the array substrate, the signal line is readily broken due to fluctuations in a manufacturing process and a device, or environmental influences.